Lithographic best condition, such as best focus or best energy, is generally determined by Focus Exposure Matrix (FEM) approach. However, the analysis of FEM (Bossung Curve to ED-windows) requires complicated software code. Thus, extracting the best focus and exposure settings of a lithography tool requires purchase of expensive software to perform automated FEM analysis. Moreover, this solution is difficult to be integrated into inline Statistical Process Control (SPC) or Automated Process Control (APC) system.
From the foregoing discussion, it is desirable to provide a simplified and cost saving method to determine the process condition of a lithography tool. It is also desirable to provide a method to determine the process condition of a lithography tool which can be integrated into inline SPC or APC system.